Tissue culture methodologies allow physiological reactions and occurrences to be studied outside the organism without the influence of other biological reactions.
Incubation of tissue slices for short periods (hours) was introduced for biomedical studies in 1923 by Warburg. Prolonged incubations (days/weeks) were in practice, not possible until the 1950's, following the introduction of antibacterial and antifungal antibiotics.
There must be uniformity between each individual tissue sample for uniformity and reproducibility among experiments for a tissue culture methodology to be effective. In the past, the production of homogeneous tissue slices from fresh tissue samples has been difficult and dependent on the skill and the experience of the technician. Attempts to produce tissue samples which are uniform in dimension have been met with problems including irreproducibility of slice thickness, contamination of tissue samples and irregular, nonreproducible trauma to the tissue adjacent to the cutting surface.
In U.S. Pat. No. 5,148,729, the applicant disclosed a biological tissue slicer which allowed an inexperienced technician to produce nearly identical tissue slices in an aseptic environment while minimizing tissue trauma. The invention included a blade held in a blade holder between two pins while one or more permanent magnets provide a constant downward pull on the blade and blade holder. The design eliminated need for readjustment or tightening which are opportunities for contamination. The reproducibility of tissue slices is increased as vertical "chatter" of the blade decreases. Also, the exposure of the tissue sample to the blade is limited to reduce the extent of trauma to the cut surface of the tissue.
The Krumdieck device has some disadvantages which do not facilitate the most effective means of slicing tissue. The pumping and trap system of the Krumdieck device complicates the design of the tissue slicer and makes manufacturing the machine more complicated thereby increasing production costs. Krumdieck uses an electric motor mounted in the base to drive a reciprocating blade holder. The motor drives an eccentric pin to convert the rotation of the drive shaft to linear motion in the blade holder. The base mounted motor requires a sealed shaft which extends upward into the buffer reservoir. The seals not only increase production cost but prevent the slicer assembly from being fully autoclavable. The ability to autoclave the entire slicer assembly is crucial to minimize contamination of the tissue samples. Contaminated samples lead to erroneous or unusable information which hampers important and costly research. A simple autoclavable tissue slicer apparatus with a mechanical wash stream pump which is simple and inexpensive to manufacture is needed for biological tissue sampling in the biochemical, pharmacological or toxicological sciences.